cGVHD induces prolonged behavioral deficits. (A) Schematic of transplantation regime. Lethally irradiated B6D2F1 (H2^b/d) recipient mice received 5 × 10⁶ TCD BM with no T cells or with 0.5 × 10⁶ CD3⁺ T cells from C57Bl/6 (H2^b) donors to induce low-grade nonlethal cGVHD. (B) Schematic of transplantation regime. Ten × 10⁶ BM with or without 5 × 10⁶ CD3⁺ T cells from a BALB/c (H2^d) donor were transplanted into lethally irradiated C57Bl6 (H2^b) recipients. (C) Time B6D2F1 recipients spent swimming (mobile) in the forced swim test at days 35 and 70 after transplant (day 35: n = 6-8 mice per group; representative of 2 independent experiments; day 70: n = 9-10 mice per group). (D) Time C57Bl6 recipients spent swimming (mobile) in the forced swim test at days 35 and 70 after transplant (n = 8-9 mice per group). Performance of cGVHD and TCD mice in the active place avoidance task for assessment of spatial learning in 20-minute sessions across 5 days beginning at day 35 (E) or 70 (F) after transplant (n = 9-10 mice per group). Recorded parameters include improvement from day 1 to 5 expressed as a percentage (calculated based on the difference in the number of entries into the shock zone), total number of entries into the shock zone per day, and maximum time spent avoiding the shock zone per day. Data are presented as mean ± standard error of the mean. Statistics: unpaired Student t test for differences between GVHD and TCD mice (improvement) (B,D-F), and repeated measures 2-way analysis of variance followed by Bonferroni post hoc comparison (entries, avoidance time) (E-F). *P < .05, **P < .01, ****P < .0001.